Future Orchards Trial Outline
Project title:
Region:
Contact person:
Projective
Objective:
Best fertigation practices for optimum young apple tree growth
Western Australia
Rachelle Johnstone
To determine the best time to apply fertilisers via fertigation during an
irrigation event for optimum tree growth by monitoring the movement of
nitrate fertilisers in the root zone of young apples trees.
Outline/method/
(what we will do):
This demonstration will be a continuation of the trial carried out last season.
In each selected block, two FullStop® wet front detectors have been installed
within the root zone of the tree rows. One at a depth corresponding to the
middle of the root zone depth; the second one below the bottom of the root
zone. Tensiometers have been installed in the same blocks.
An in-line water meter has been installed to record the actual volume of
water applied during each monitored event and during the whole irrigation
season.
As growers apply fertilisers via fertigation, it is hoped to collect soil solution
from the FullStops during and shortly after a fertigation event.
The level of nitrate in the soil solution will be measured using nitrates test
strips Merckoquant®.
Records will be made of:






The amount of fertiliser applied
The timing and duration of the fertiliser injection.
The duration of the irrigation.
The level of nitrates present in the soil solution at both depths of the
root zone.
Soil moisture level at the time of the fertigation
Total volume of water actually applied
Similar recordings will be made for at least three fertigation events on each
block.
The demonstration set up allows for growers to collect their own soil solution
sample and measure nitrates.
If nitrates are detected below the bottom of the tree root zone, the grower
will be advised and a different strategy of application will be suggested and
discussed.
Tree growth will be recorded by measuring: tree height monthly; trunk
circumference area and tree row volume annually.
In addition leaf samples will be collected from each site to assess the
nutrition status of trees.
Local growers are keen to find out where their fertiliser dollars go and are
supportive of this demonstration.
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Milestones
Trial defined
Trial setup
Records Measurement 1
Field day
Records measurement 2
Reporting
Presentation growers
Planned Date or Completion Date
30/09/2012
31/10/2012
Post harvest
30/06/2014
Post harvest
Map & Layout:
2
Future Orchards Trial: Final Report
Project title:
Region:
Contact:
Projective
Objective:
Best fertigation practices for optimum young apple tree growth
Western Australia
Rachelle Johnstone
To determine the best time to apply fertilisers via fertigation during an
irrigation event for optimum tree growth by monitoring the movement of
nitrate fertilisers in the root zone of young apples trees.
Outline/method/
This demonstration was a continuation of the trial carried out last season on
two Kanzi® blocks at Newton Orchards of Manjimup. Last season two
FullStop® wet front detectors were installed within the root zone of the tree
rows: one at a depth corresponding to the middle of the root zone depth and
the second below the root zone. The wet front detectors provided a quick
visual tool to check the depth of each irrigation event, and a way to collect
soil solution for nutrient (nitrate) analysis.
(what you did ):
Tensiometers were also installed and readings recorded by the orchard
manager regularly. An in-line water meter was installed to record the actual
volume of water applied during each monitored event and during the whole
irrigation season.
Soil solution was collected from the FullStops during and shortly after three
fertigation events. The level of nitrate in the soil solution was measured
using nitrates test strips Merckoquant®.
Tree growth was recorded by measuring: tree height; trunk circumference
area and tree row volume annually.
3
Results Summary
Water use
Records of hours of irrigation were taken over the season and the total amount applied was
equivalent to 1.4ML/ha or 672 L/tree/season. Using local rainfall and evaporation data this amount
is approximately 40% of the theoretical estimated water use (Figure 2).
Readily Availiable moisture (Liters / Plant)
Change in Rootzone Available Water
20
15
10
Soil moisture
(recommended)
Soil moisture farm
application
Field Capacity
5
0
-5
-10
Allowable moisture
deficeit
-15
-20
-25
1
2
3
4
5
6
7
8
9 10 11 12
Month
Figure 1 shows the indicated irrigation pattern has severe stress periods throughout the irrigation
season. The graph shows that farm run times are too long and irrigation is not frequent enough to
meet daily tree water demand. The trees are regularly pushed into stress between irrigations with
the top up irrigation cycle resulting in deep perculation and water lost below the feeding root zone.
Cumulative Water Use
12
10
ML / Zone
8
Cumulative water use
(recommended)
6
4
Cumulative water use
farm
2
0
1
2
3
4
5
6
7 8
Month
9
10 11 12
Figure 2 shows the total amount of water applied to the blocks (3.3ha total area) over the season is
significantly lower than the recommended amount.
4
Component Application of Water
35
Liters / Plant
30
25
20
Actual applied daily
per plant
15
Daily Deep Percolation
per plant
10
Daily Plant
Requirement
5
0
1
2
3
4
5
6
7
8
9 10 11 12
Month
Figure 3 shows that there the irrigation schedule did not meet the daily plant water requirement for
extended periods throughout the season. It also shows that periods of extended irrigation run times
result in water moving past the root zone.
Soil moisture monitoring
Tensiometers were installed between 2 drippers, in the tree root zone at depths of 25, 40 and 60
cm. Tensiometers readings were taken regularly by the orchard manager.
Two FullStop™ wet front detectors (www.fullstop.com.au ) were installed at depths of 30 and 50 cm.
The orchard manager checked the FullStops after each irrigation event.
Block 23
16
Tension (kPa)
14
12
10
25cm
8
40cm
6
60cm
4
2
0
25-Oct-13
25-Nov-13
25-Dec-13
25-Jan-14
25-Feb-14
Figure 4 shows tensiometer readings for block 23 over the season
5
25-Mar-14
Block 24
16
Tension (kPa)
14
12
10
25cm
8
40cm
6
60cm
4
2
0
25-Oct-13
25-Nov-13
25-Dec-13
25-Jan-14
25-Feb-14
25-Mar-14
Figure 5 shows tensiometer readings for block 24 over the season
Block 23
Irrigation run time (hours)
16
14
12
<30cm
30cm
50cm
10
8
6
4
2
0
25-Oct-13
25-Nov-13
25-Dec-13
25-Jan-14
25-Feb-14
25-Mar-14
Figure 6 shows the irrigation events recorded over the season for block 23. The events in blue
indicate that water did not move past 30cm for that event. The red events moved past 30cm and the
green events moved past 50 cm as indicated by the FullStop wetting front detector.
Block 24
Irrigation run time (hours)
16
14
<30cm
30cm
50cm
12
10
8
6
4
2
0
25-Oct-13
25-Nov-13
25-Dec-13
25-Jan-14
6
25-Feb-14
25-Mar-14
Figure 7 shows the irrigation events recorded over the season for block 24. The events in blue
indicate that water did not move past 30cm for that event. The red events moved past 30cm and the
green events moved past 50 cm as indicated by the FullStop wetting front detector.
Monitoring of nitrate fertilisers
Soil solution samples were collected from the SSET and full stops during three fertigation events on
29 January, 6 and 13 February 2014.
During the fertigation event, the presence of nitrates in the irrigation water was detected using
Merckoquant® test strips 0-500 mg/l NO3. Nitrates were detected in the solution from the FullStop
at 50cm after each event suggesting some leaching below the root zone. There is a lack of a clear
pattern of nitrate migration in the soil profile hours after the fertiliser application in the three
events.
Production
In 2014 40 bins were picked from block 23 and 48 bins from block 24 (pack out values not available
at time of writing this report). This equates to around 35 tonnes for the two blocks which is
approximately 10.6 tonnes per hectare.
Tree growth
Figure 8 shows tree growth on block 24 from September 2012 to March 2014.
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Table 1 shows tree growth measurements for block 24 from 2012 – 2014.
Kanzi®-block 24
Tree height (m)
Tree Row Volume (m3/ha)
Average tree girth (mm)
Trunk Circumference Area (cm2/tree)
% full canopy
Average branches/tree
Sept 2012
2
1000
84
5.6
25
3
Jan 2013
2.2
>15
Sept 2013
2.25
2750
105
8.8
40
10
Apr 2014
2.5
4250
50
-
Sept 2013
2.25
2375
95
7.19
30
7
Apr 2014
2.5
3875
50
Table 2 shows tree growth measurements for block 23 from 2012 – 2014.
(Kanzi®-block 23)
Tree height (m)
Tree Row Volume (m3/ha)
Average tree girth (mm)
Trunk Circumference Area (cm2/tree)
% full canopy
Average branches/tree
Sept 2012
2
1125
80
5
15
3
Jan 2013
2.4
>15
Conclusions/Implication
Assessing the movement of nitrate fertilisers in the tree root zone requires more sites and/or a
greater numbers of events monitored to get a better picture of what is really going on.
The current irrigation practice is not meeting the requirements of the trees. As this is a young block
it may have a negative impact on future production and performance.
Acknowledgements
We would like to thank Newton Orchards of Manjimup for allowing us to carry out the trial on their
Starkies road property and orchard manager Ben Wilson for help with collecting data over the
season.
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